Perplexity's Comet AI browser may have some concerning security flaws which could let hacker hijack your device

• SquareX discovered hidden MCP API in Comet browser enabling arbitrary local command execution
• Vulnerability in Agentic extension could let attackers hijack devices via compromised perplexity.ai site
• Demo showed WannaCry execution; researchers warn catastrophic third‑party risk is inevitable

Cybersecurity experts at SquareX claims to have found a major vulnerability in Comet, the AI browser built by Perplexity, which could let threat actors take over the victim’s device, entirely.

SquareX found the browser has a hidden API capable of executing local commands (commands on the underlying operating system, as opposed to just the browser).

That API, which the researchers named as MCP API (chrome.perplexity.mcp.addStdioServer), appears to be a custom implementation of a more general “Model Context Protocol”, and “allows its embedded extensions to execute arbitrary local commands on users’ devices, capabilities that traditional browsers explicitly prohibit.”